Aryldiazene complexes

Insertion of mono- or bis(aryldiazonium) cations into the Re—bonds of the hydride complexes [ReH(CO)5 (PR3)J (PR3 = P(OEt)3, PPh(OEt)2, PPh2(OEt) =1 ) results in the formation of cationic aryldiazene complexes of the compositions [Re(HNNAr)(CO)5 (PR3) ]" or [ Re(CO)5 (PR3) 2(/r-HNNArNNH)] +. " Bifunctional diazene/diazonium derivatives which can be prepared in this way are excellent building blocks for heterobinuclear and heterotrinuclear compounds with bis(aryldiazene) bridging ligands as has been demonstrated for Re-Ru, Re-Os,... 

Aryldiazene complexes can be formed from arenediazonium ions and metal hydrides, and subsequent deprotonation leads to aryldiazenido complexes. Mechanistic details of ArN insertion into Rh—H and Pt—H bonds have been recently studied (equations 124-126).453 454... 

Both H-NMR and Raman spectroscopy have been used to identify aryldiazene complexes (184, 218, 268). However, fluorescence of [Ru-Cl(CO)2(HN2Ph)(PPh3)2] leads to poor quality of Raman spectra, and rapid exchange in polar solvents of the nonaromatic diazene proton does not allow its detection by NMR spectroscopy. 

The overall reaction from 10.25 to 10.26 is an insertion into a metal-hydrogen bond. It is, however, only an apparent insertion, as the Rh — H bond dissociates in the diazene diazenido equilibrium (10-9), as already emphasized by Sutton in 1975. Other interesting cases are the reactions of tungsten mono- and bis-hydrido complexes with diazonium salts. The monohydrido complex 10.27 yields the aryldiazene complex 10.28 (Smith and Hillhouse, 1988) in an 1,1-insertion (10-11). The bishydrido complex 10.29 (10-12), however, adds one of the two H-atoms at the... 

Cationic dihydrogen complexes of the type [TpRu(L)(L )(H2)] (L = P(OEt)3, PPh(OEt)2, L = PPhs, L = L = P(OEt)3) have been utilized to prepare various RuTp diazenido compounds. Treatment of [TpRu(L)(L )2(H2)] with aryldiazonium salts give aryldiazenido complexes [TpRu(L)(L )(NNAr)]. Analogous reactions were performed with hydrazines. With monohydrido complexes TpRuH(L)(L ) and aryldiazonium salts, aryldiazene complexes [TpRu(L)(L )2(NH=NAr)]" were obtained. 

The aryldiazenate complex, [Ru(bipy)2(N2C6H4Me)Cl]2+, in acetonitrile solution, undergoes an irreversible one-electron oxidation,34 Eq. 7.3 ... 

There are fewer documented examples of these N2-elimination reactions than might be expected. Aryldiazenido complexes are known to react with molecular hydrogen to yield arylhydrazine complexes via aryldiazene intermediates (equations 158 and 159). 

Cyclobutenes, in Pauson-Khand reaction, 11, 352 Cyclocarbonylation reactions, alkynes, 10, 714 Cyclo-C3 complexes, with molybdenum carbonyls, 5, 440 Cyclo-C4 complexes, in molybdenum carbonyls, 5, 448 Cyclochrome P450cam, aryldiazene reactions, 6, 107 Cyclodextrins... 

Irradiation of pentacarbonyl iron in the presence of l-tc/t-butyl-2-aryldiazenes 163 produced in the first step the orf/jo-metallated complexes 164, which in the next thermal step... 

The reactions of cytochrome P450cam with aryldiazenes (ArN=NH) yield cr-bonded iron-aryl complexes, whose oxidation causes regioselectivc migration of the aryl group from the iron to the porphyrin nitrogens. The influence of high pressure on the formation and rearrangement of these Fe-aryl complexes was studied. The aryls are stable at atmospheric pressure but decompose in a pressure-dependent manner at pressures above 1,500 (Fe-phenyl) or 2,500 bar (Fe-(2-naphthyl) or Fe-(/>-biphenyl)) under formation of the A-aryl protoporphyrin adducts. ... 

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